An efficient usage of electrical energy is the determining solution in order to avoid future electricity shortage problems. Power electronic systems deliver a major contribution to efficiency improvements.
The use of electrical rectifier circuits has been well known for many years. The more simple circuits, but yet more reliable ones are those with passive diodes, more advanced rectifiers uses fast switching transistors, in between there are endless combinations of both.
The required number of power electronic systems can only be installed, if the harmonic distortions, which are produced by these systems, can be minimised.
Although the trend over the last decades has been towards more advanced power electronic rectifiers with high frequency switching and minimized magnetic components, there are still many applications where simple power electronics combined with advanced magnetics outperform the other.
Increased regulatory requirements for better power factor and low harmonic distortion factor have challenged the circuit design; these regulatory requirements apply to many geographical areas, and thus a global design with good power factor is to prefer. The simple rectifiers of the prior art suffer from having a low power factor compared to the fast switching rectifier circuits with build in power factor correction. Thus there has been a need for circuits with improved power factor.
In the prior art tuned harmonic filters have been used to reduce harmonics, but they have limited performance and suffer from other disadvantages. Passive multi-phase current or voltage splitters are cost efficient, compact and highly reliable harmonics mitigation concepts for three-phase loads.
The adequate coupling of current splitting transformers allows for a massive reduction of the magnetic volume as well as for the replacement of complex circuits by one single component.
The power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load, to the apparent power in the circuit. Thus a unity power factor can be reached when the voltage and current are in phase with each other.
The harmonic distortion is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency.
An objective of the invention can be seen as providing a rectifying circuit with a high power factor, especially during full load, furthermore it is also an objective to provide a rectifier that operates with an optimal power factor in a broad load range.